In a cataract operation, removing an opacified lens by phacoemulsification (PEA), and implanting an intraocular lens after removing an opacified lens are widely performed. Intraocular lenses include: a hard intraocular lens whose optical portion is made of a hard material such as PMMA (polymethylmethacrylate), and a soft intraocular lens which is made of a soft material such as silicone elastomer, soft acrylic, or hydrogel.
When using a hard intraocular lens, the intraocular lens must be inserted through an incision formed in the cornea or sclera that is of the same or slightly wider width than the diameter of the optical portion. On the other hand, when using a soft intraocular lens, folding of the optical portion allows the intraocular lens to be inserted into the eye through an incision smaller than the diameter of the optical portion.
FIGS. 12(A) and 12(B) show a soft intraocular lens of this kind. A front view is shown in FIG. 12(A) and a side view is shown in FIG. 12(B). In practice, a soft intraocular lens 100 of this kind is formed in a flat circular shape and comprises an optical portion 101 serving as a crystalline lens in an eyeball and two supporting portions 102, 102 formed in a linear shape. These two supporting portions 102, 102 are provided at two symmetrically opposite sections on the circumference of the optical portion 101. The supporting portions 102, 102 are extended in the form of a circular arc in such a manner as gradually departing away from the outer fringe of the optical portion 101 at a curvature slightly larger than that of the outer fringe of the optical portion 101.
The soft intraocular lens 100 of this kind is designed so as to be able to be inserted through a small incision into an eye after the optical portion 101 thereof is folded in two by an intraocular lens insertion device disclosed, for example, in Intl Application Publication Pamphlet of WO2006/090531 or Japanese Unexamined Patent Application Publication No. 2004-351196.    Patent Document 1: WO2006/090531 Intl Application Publication Pamphlet    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2004-351196